Printheads in inkjet printers are typically formed with a plurality of layers that are laminated together to form the printhead. Each printhead is fluidly connected to one or more ink sources to enable liquid ink to flow into the printhead. The liquid ink then moves through passageways formed in the layers to a plurality of chambers, each of which is opposite an actuator, such as a piezoelectric transducer. When the actuators are activated by an electrical driving signal, a diaphragm is deflected with reference to the chamber to eject a drop of ink from the chamber through a nozzle. By selectively activating the actuators, ink drops are ejected to form an ink image on an ink receiving surface. Typically, a flex circuit layer is formed with electrical traces that are operatively connected to a driving signal circuit to deliver the electrical driving signals to the actuators.
The passageways in a laminated printhead are formed by aligning passageway openings in adjacent layers to enable ink to exit a passageway in one layer and enter a passageway in the next layer. Consequently, the alignments and tolerances for the distances between openings in adjacent layers are tight to prevent ink from escaping the passageways and migrating along other features in the printhead. One layer that can present issues with these tolerances is the flex circuit board. A flex circuit board includes a foundational flexible material with a pattern of an electrical conductor, such as copper, on one surface of the foundational material. The electrical conductor pattern can be produced on the foundational material using either an additive process or a subtractive process. The height differences between the electrical conductor pattern and the exposed foundational material enable ink to seep out the passageways through the foundational flexible material before it enters the passageway in the next layer. Preserving the integrity of ink passageways through a flex circuit board would be beneficial